1. Field of the Invention
The present invention pertains to apparatus for handling metal strip coils and more particularly to apparatus for helically coiling bands after slitting a wide strip. The apparatus of the invention may also be employed for helically coiling bands made from flexible materials other than metallic ones, such as from plastics.
2. Description of the Prior Art
Metal bands are generally produced by lengthwise slitting a continuously moving wider strip, and each band is then coiled on an individual reel. When the bands are narrow, it is desirable to coil them on reels in a helical manner, i.e. to guide a band back and forth along the reel axis in the course of coiling. However, helical coiling poses a problem as to an even laying of the band convolutions and maintaining of a constant band tension as the coil diameter increases. For an adequately shaped coil to be formed, such variables as the reel rotation speed, band tension, and coiling pitch must be maintained at predetermined values, which in many cases is hard to attain.
Attempts have been undertaken to solve this problem by the provision of coiling apparatus wherein the rotation speed of the reels is dependent upon the band tension, of individually-driven coiling drums, of self-contained apparatus and processing lines.
Among numerous constructions directed at solving the problem of helically coiling bands there is known an apparatus disclosed in U.S. Pat. No. 3,587,993. The apparatus comprises a strip uncoiler, a strip-joining device, a slitter for lengthwise slitting of strips into bands, a band separator, and a coiler. The band separator comprises a plurality of rollers arranged in a row and having vertically extending axes. When passing between the band separator rollers, the bands moving in a horizontal plane are twisted through 90.degree. and then enter the coiler zone. The coiler comprises two rows of reels each arranged on a vertical axis and provided with an individual drive.
The reels are installed on a common frame in a horizontal plane. Mounted on the common frame for a vertical movement are two horizontal rails carrying vertical-axis rollers. Each roller is disposed in front of its reel and has an annular groove defined by a flange and a collar movable along the roller axis and adapted to receive a metal band. The collar can be adjusted along the roller axis to vary the width of the groove in accordance with the band width. In the course of helically coiling bands on the reels, the rails with the rollers are raised and lowered by a hydraulic cylinder actuated from a hydraulic pump which provides for a controlled feed of a hydraulic fluid to the hydraulic cylinder. The hydraulic pump is driven by a chain and sprocket drive from the shaft of the front-end reel, which impairs the accuracy of maintaining the tension of the band coiled on this reel and may cause a break of the band. The direction of movement of the rails is reversed by means of a limit switch which, when the rails reach their extreme positions, operates a 4-way valve, causing the piston of the hydraulic cylinder coupled to the rails to move in the reverse direction.
The above-described apparatus features large dimensions and, accordingly, a heavy weight. The use of individual drives of the coiling units makes the coiling station more difficult to attend and increases the cost of the apparatus. Finished coils must be removed by hoisting means in turn from each reel, which lengthens the processing cycle.
The use of rollers with annular grooves for guiding bands restricts the range of strips in terms of thickness thereof, since the edges of thin bands get damaged as the bands shift along the axis of the roller; furthermore, such a construction of the rollers calls for an additional time to change the groove width.
Thus, upgrading the quality of coils, extending the range of bands and raising the productive capacity of the apparatus are hindered by the arrangement of the drive of the reels and by the band guiding means which comprises rollers with an annular groove.
The present invention has as its object to provide an apparatus for helically coiling bands, which ensures a better quality of produced coils, is suitable for coiling of a wider range of bands, and offers a higher productive capacity owing to interdependence between constancy of the tension of the bands, the rotation speed of coiling drums, and the coiling pitch.